1. Field of the Invention
Exemplary embodiments of the present invention relate to an antenna system for radio communication; and, more particularly, to an antenna system having adaptive polarization control so as to control polarization resources of a radio communication antenna on an environment/time basis.
2. Description of Related Art
In general, a radio communication system (e.g. radio terrestrial or satellite communication system) uses a predetermined frequency to transmit and receive data information wirelessly. The radio communication system has an antenna on its front-end as an important element for transmitting and receiving radio signals. Such an antenna needs to be constructed so as to transmit and receive radio waves efficiently. Therefore, there is a wide range of research and development in progress in connection with antennas.
Generally used high-frequency antennas include dipole antennas, monopole antennas, patch antennas, horn antennas, parabolic antennas, helical antennas, and slot antennas. Such antennas are used and applied variously with regard to the communication distance and service area.
Essential resources of a radio communication system include frequency, polarization, space, and direction. Recent increase in the type of radio communication services is followed by depletion of frequency resources, which are the most important resources of radio communication. In addition, the trend towards broadband services requires MIMO (Multiple Input Multiple Output) communication technology.
The MIMO communication technology employs multiple antennas and transmits data through multiple channels which are independent from each other, thereby increasing communication capacity. However, the majority of current radio communication terminals for MIMO communication or repeater/base station antennas use fixed polarization.
Such a fixed-polarization antenna system structure has a problem in that the service quality may be degraded by interference of services, for example, when services are expanded and provided through broadband in the future. Solving this problem requires an antenna system configured to variably control antenna polarization on a time basis in conformity with radio environments and system requirements.